Nordic Winter Meeting on Physics @ FAIR

In order to provide more data on the T=1 halo state of the six-nucleon system, in particular to investigate the importance of triton-triton and triton-3He clustering, we have made an experiment studying the 3He(3He,6Li*)\pi+ reaction at CELSIUS storage ring in Uppsala. The J\pi=0+, T=1 state at 3.56 MeV in 6Li is believed to have a similar structure as its analogue state; the two-neutron halo ground state of 6He. The formation of the specific state of 6Li in the pionic fusion of alpha particles and deuterium was studied previously [1], 1.2 and 1.9 MeV above threshold. The total cross section for the two energies was found to be 228+-6 (stat) nb and 141+-12 (stat) nb respectively. We have measured the cross section for the 3He(3He,6Li*)\pi+ reaction 1.2 and 1.9 MeV above threshold. The Coulomb corrected cross section is determined to be 183+-41 (stat) nb and 87+-54 (stat) nb, respectively, which is of the same order of magnitude as for the (d,4He) initial state [1]. This is an indication that 3N-3N clustering is indeed important for the description of the ground state of 6He and its analogue state in 6Li as pointed out by Arai Suzuki and Lovas [2]. Technical details of the experiment along with the results from the analysis will be presented. References: [1] M.Andersson et al. Nuclear Physics, A 779 (2006) 47 [2] K. Arai, Y. Suzuki, R.G. Lovas, Phys. Rev. C 59 (1999) 1432